> For the complete documentation index, see [llms.txt](https://onestopconcept.gitbook.io/open-endpoints/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://onestopconcept.gitbook.io/open-endpoints/configuration/application-directory-structure/security.xml.md).

# security.xml

The **mandatory** file `security.xml` under the application directory comprises of one or many secret keys, which are used to calculate hash keys. See: [Authentication](/open-endpoints/usage/authentication.md)

![security image](https://cdn.openendpoints.io/images/gitbook/security-xml-image.png)